Identifying Sulfur Deficiency with Tissue Testing
When considering Liebig’s Law of the Minimum, sometimes the most limiting factor is due to a nutrient interaction. For example, if both sulfur (S) and nitrogen (N) are limited, then an application of either one might not improve yields or deficiency symptoms.
In this article, researchers at Purdue University explain the relationship between nitrogen and sulfur within the plant in order to diagnose nutrient deficiency in wheat. Since the ratio of sulfur to nitrogen in proteins is 1:15, that same ratio, in combination with sulfur concentration, can be applied to tissue samples. In general, the lower the sulfur concentration and higher the N:S ratio, the more likely sulfur is deficient. For example, if tissue sulfur concentration is less than 0.12% and the N:S ratio is 20:1, then sulfur is deficient.
If sulfur is limiting, additional applications of nitrogen could make the deficiency symptoms worse and worse yet, not improve yield. This approach might not apply to all crops either. Sulfur deficiency is most common in corn, wheat, and alfalfa, but not necessarily in soybean.
For more information on other interactions, check out how phosphorus and nitrogen can boost corn yields.
